大时滞网络拥塞控制器的设计

几乎现有的AQM算法都忽略了大时滞对网络拥塞控制系统稳定性的负面影响,以致稳定性、响应性和鲁棒性在大时滞网络中大大降低.如PI、REM等AQM算法在大时滞环境下表现出剧烈的队列震荡和频繁的空队列情况,这些现象直接导致了链路利用率的低下和延时抖动的增大.而面向大时滞网络拥塞控制的DC-AQM算法不够恰当的参数配置使得系统输出偏离了控制的目标,出现了很高的分组丢弃概率.为解决大时滞网络拥塞控制的稳定性问题,本文基于内模控制原理,提出一种新的鲁棒AQM控制器IMC-PID来补偿网络时滞对系统稳定性的影响.仿真分析表明,随着网络时滞的增大,IMC-PID在综合性能上胜过其他算法,获得了较高的链路利用率和较低的延时抖动.     

基于鲁棒优化算法的小型无人机模糊控制器研究

简要论述了小型无人机的经典H2/H∞鲁棒优化算法,并在此优化控制算法基础上,对模糊控制器开展了研究,模糊控制器的知识库主要依据原型无人机的实验数据搭建。为了验证模糊控制器的控制品质和鲁棒性,在小型无人机的静态参数(高度、角度)控制回路上将模糊控制器与原型控制器进行了结合,使之成为鲁棒模糊控制器。对小型无人机鲁棒模糊控制系统参数的控制品质和鲁棒性进行了计算,并将这些特性和原型机进行了比较。仿真结果表明,采用模糊控制器的控制系统鲁棒性提高了近一个数量级。     

基于PI迟滞模型的压电陶瓷复合控制算法研究

为减小压电陶瓷的迟滞非线性对系统跟踪精度的影响,该文采用经典的存在逆解析的PI迟滞模型对压电陶瓷的迟滞特性进行建模,将PI模型的逆模型用于压电陶瓷的前馈控制算法中,然后设计了神经元比例、积分、微分(PID)反馈控制算法,将前馈控制算法与神经元PID反馈控制算法结合得到了压电陶瓷的复合控制算法。将仅含前馈的控制算法和复合控制算法在压电陶瓷的控制器上执行,实验结果表明,仅含前馈的控制算法的跟踪误差为1.256μm,而复合控制算法的跟踪误差仅为0.092μm,该复合控制算法使跟踪精度提高了1.164μm。     

基于PI迟滞模型的压电陶瓷复合控制算法研究

为减小压电陶瓷的迟滞非线性对系统跟踪精度的影响,该文采用经典的存在逆解析的PI迟滞模型对压电陶瓷的迟滞特性进行建模,将PI模型的逆模型用于压电陶瓷的前馈控制算法中,然后设计了神经元比例、积分、微分(PID)反馈控制算法,将前馈控制算法与神经元PID反馈控制算法结合得到了压电陶瓷的复合控制算法。将仅含前馈的控制算法和复合控制算法在压电陶瓷的控制器上执行,实验结果表明,仅含前馈的控制算法的跟踪误差为1.256 μm,而复合控制算法的跟踪误差仅为0.092 μm,该复合控制算法使跟踪精度提高了1.164 μm。     

一种基于IP网络的拥塞控制调度算法

文中在TCP基于窗口的端到端的拥塞控制算法和IP层拥塞控制算法上提出了一种改进的增强型非线性比例积分算法,该算法主要解决PID算法的参数设置、鲁棒性和算法敏感性问题,减少了PID算法的参数设置.改进的算法采用了内模控制和优化控制来实现算法的稳定性.通过仿真实验证明提出的算法有快的收敛速度和稳定性,提高了算法的鲁棒性.     

灰色PID控制在AUV横滚控制中应用研究

针对AUV航行环境复杂、模型参数摄动大、执行机构的饱和非线性等特点,采用灰色预测算法改进传统的AUV PID横滚姿态控制器,设计了灰色PID控制算法,以达到抑制和消除横滚的目的。仿真结果表明,灰色预测PID算法操舵平滑,控制速度快,鲁棒性和环境适应能力更好,完全能胜任AUV横滚姿态控制的要求。     

四旋翼无人机设计与滑模控制仿真

随着近些年自然灾害的频繁发生,四旋翼飞行器搜救设备得到越来越广泛的应用。首先介绍四旋翼飞行系统的总体设计架构,然后针对地面坐标系与集体坐标系建立了四轴飞行器的动态模型,同时为得到良好的响应速度、控制稳定度与鲁棒性,应用滑模变结构控制理论设计了飞行器的控制算法。最后通过仿真数据对相同条件下的PID控制器与该控制器对比,证明该控制器的强鲁棒性和控制稳定性满足项目任务需求。     

闭环增益成形控制新算法及其应用

受到回路成形思想的启发,通过对Ｈ∞控制的Ｓ／Ｔ混合灵敏度奇异值曲线的观察及Ｓ和Ｔ的相关性给出一种新的基于闭环增益成形的控制算法,该算法避免了权函数的选择而对系统进行闭环增益成形,其核心是确定闭环系统传递函数即Ｔ的最后希望的开头,用闭环系统具有工程意义的参数直接构造出鲁棒控制器,从根本上保证了设计出的控制器具有良好的鲁棒性和鲁棒稳定性,基于该算法给出了一种新的船舶鲁棒控制算法,该算法的优点是设计过程     

互联网中的不确定时滞全局滑模AQM算法

为解决互联网中的拥塞现象,基于全局滑模理论,提出了一种主动队列管理算法.将互联网中的不确定因素等效为拥塞控制模型的参数摄动,并考虑到时变时滞因素,利用线性矩阵不等式设计了渐近稳定的全局滑模面,使系统运动的全程都是滑动模态,显著提高了系统的鲁棒性.并且所设计的控制器能够有效降低路由器中队列长度的稳态振荡.仿真对比表明,所提出的算法具有更高的稳定性和鲁棒性,能够适应复杂多变的互联网环境.     

基于多自由度性能指标的模型预测控制算法

 传统的模型预测控制算法是一自由度控制器,不具有使系统的目标跟踪特性和干扰抑制特性同时到达最佳的能力.本文提出一种基于多自由度性能指标的模型预测控制算法,对设定值跟踪、抗可测扰动、抗不可测扰动与模型失配等情况,允许设置不同的响应参数,提高了控制器品质.仿真结果表明了算法的有效性.     

LMS算法的二次稳定性及鲁棒LMS算法

本文在时域内研究LMS算法(least mean square algorithm)的稳定性及鲁棒LMS算法的构造.首先将LMS算法表达式转化为标准的离散时间系统状态方程形式,之后运用线性矩阵不等式(LMI)技术对其二次稳定性进行了分析.针对滤波过程中会出现的输入和测量噪声干扰,本文提出了一种兼顾收敛性、鲁棒稳定性以及鲁棒性能的鲁棒LMS算法,最后给出了仿真算例,通过和一般的LMS算法的比较,体现了这种鲁棒LMS算法的优越性.     

A robust distributed controller of a single-link SCARA⧹Cartesian smart materials robot

In this paper, dynamic modelling and controller design are presented for a SCARA⧹Cartesian smart materials robot, a flexible SCARA⧹Cartesian robot bonded with piezoelectric actuators and sensors for better control performance. Conventionally, controller design is usually carried out for a truncated model of partial differential equations (PDEs). In this paper, a novel distributed controller is developed directly based on PDEs, which can guarantee the globally exponential stability of the closed-loop system. Taking into account of bounded disturbances, a robust distributed controller is further developed and stability proof is also given. Different from the conventional approach, truncation is introduced at the stage of the controller implementation. Stability proofs show that the proposed controller can also stabilize the finite dimensional model with arbitrary number of flexible modes. Both simulation and experiment results verify that the robust controller can achieve good performance in the suppression of residual vibrations under the environment of disturbances.     

Performance tuning of robust motion controllers for high-accuracy positioning systems

This paper presents a structural design method of robust motion controllers for high-accuracy positioning systems, which makes it possible to tune the performance of the whole closed-loop system systematically. First, a stabilizing control input is designed based on Lyapunov redesign for the system in the presence of uncertainty and disturbance. And adopting the internal model following control, robust internal-loop compensator (RIC) is proposed. By using the structural characteristics of the RIC, disturbance attenuation properties and the performance of the closed-loop system determined by the variation of controller gains are analyzed. Next, in order to design a robust motion controller for a high performance positioning system, dual RIC structure is proposed and it is shown that if the synthesis of the robust motion control law is performed in the RIC framework, the robust property of RIC can be naturally implanted in the feedback controller. The proposed structural design of robust motion controller provides a systematic approach to the problem of robust stability and performance requirement in the face of uncertainty. Furthermore, by allowing the tradeoffs between robust stability and performance to be quantified in a simple fashion, it can illuminate systematic design procedure of the robust motion controllers. Finally, the proposed method is verified through simulation and the performance is evaluated by experiments using a high-accuracy positioning system.     

GA-based multiobjective PID control for a linear brushless DC motor

This paper presents a robust output tracking control design method for a linear brushless DC motor with modeling uncertainties. Two frequency-domain specifications directly related to the mixed sensitivity function and control energy consumption are imposed to ensure stability and performance robustness. With regard to time-domain specifications, the rise time, maximum overshoot and steady-state error of the step response are considered. A generalized two-parameters proportional, integral, and derivative (PID) control framework is developed via a genetic searching approach ensuring the specifications imposed. The proposed design method is intuitive and practical that offers an effective way to implement simple but robust solutions covering a wide range of plant perturbation and, in addition, provides excellent tracking performance without resorting to excessive control. Extensive experimental and numerical results for a linear brushless motor confirm the proposed control design approach.     

基于鲁棒稳定的闭环激磁电源幅值回路设计

保证系统鲁棒稳定,同时满足系统性能指标要求始终是控制设计的目标。该文根据转台测角系统对激磁电源稳定性和性能指标的要求,提出了采用H优化控制理论,以鲁棒稳定为基础的闭环激磁电源幅值回路设计的方法,讨论了H控制器的求解过程。经四个转台长期使用验证该设计方法的有效性和合理性,完全满足了高精度转台的需要。     

Internal model control (IMC) approach for designing disk driveservo-controller

This paper presents a design procedure for disk drive servomechanism using an internal model control (IMC) structure. A typical disk drive actuator can be modeled as second order dynamics for low frequencies. However the response at higher frequencies shows resonant behavior which is difficult to model. We discuss the use of IMC structure for designing servo-controllers for disk drives. In this method, a second order nominal model of the plant is used to design an H ₂-optimal controller to attain minimum integral-error-square (ISE) performance. Then to maintain robust stability at higher frequencies, sufficient roll-off at such frequencies is provided by an H _∞ optimization procedure. Here, the H₂-optimal control is augmented by a low pass filter with sufficient high-frequency roll-off to ensure robust stability and robust performance. A multiplicative uncertainty bound is defined using the data of the disk drive servo plant's frequency response and the response of the nominal model, and this is then used to decide robust stability and robust performance bounds. Tuning of only one parameter of the IMC filter makes this design method easy and convenient. Simulation results for the designed controller are presented     

Improved Delay-Dependent H∞ Filtering Design for Discrete-Time Polytopic Linear Delay Systems

This brief revisits the problem of delay-dependent robust H_infin filtering design for discrete-time polytopic linear systems with interval-like time-varying delay. Under the condition whether the unknown parameters can be measured online or not, a parameter-dependent or a parameter-independent filter is respectively developed which guarantees the asymptotic stability of the resulting filtering error system with robust H_infin performance gamma. It is shown that by using a new linearization technique incorporating a bounding technique, a unified framework can be developed such that the full-order and reduced-order, the parameter-dependent and parameter-independent filters can be obtained by solving a set of linear matrix inequalities. Finally, a numerical example is provided to illustrate the effectiveness and merits of the proposed approach.     

Robust performance of the multiloop perturbation compensator

A novel perturbation attenuation method is proposed for robust performance of mechanical systems. First, we give a unified view on a class of existing perturbation observers and define the residual perturbation. In terms of the view and the definition, a new perturbation compensator with multiloop structure is developed. It effectively compensates the perturbation (i.e., model uncertainty and external disturbance) to the plant in a hierarchical and recursive fashion. In the multiloop perturbation compensator (MPEC) proposed, as the number of loops increases, the external disturbance condition for system stability is greatly relaxed and the perturbation attenuation performance is gradually enhanced but the robust stability margin on the modeling error becomes more strict. A recursive algorithm for general n-loop case of the MPEC is derived. By combining the developed robust perturbation compensator with a nominal feedback controller, a robust motion controller is synthesized. Experimental results for XY positioner and 2-DOF robot arms demonstrate the excellent robust tracking performance in spite of arbitrary large perturbation inputs     

Robust position control of a magnetic levitation system via dynamic surface control technique

This paper considers the position-tracking problem of a magnetic levitation system in the presence of modeling errors due to uncertainties of physical parameters. A robust nonlinear controller is designed to achieve excellent position-tracking performance. The recently developed dynamic surface control is modified and applied to the system under study, to over-come the problem of "explosion of terms" associated with the backstepping design procedure. Input-to-state stability of the control system is analyzed, and the advantages of the dynamic surface control technique over the conventional backstepping technique are verified through both theoretical and experimental studies.